4. SERVICING PROCEDURES
GENERAL LOCATION OF CONTROLS
Fast
Response
Temperature
Sensor
CONTROL BOX COMPONENT
LOCATIONS MODELS 135 & 180
2-Staged Controller
Relay
Fig.# 8195.1
Ignition Module
(Auto Ignition Only)
22
Fig.# 8195.4
SEQUENCE OF OPERATION
INTERMITTENT IGNITION DEVICE (IID)
Boilers equipped with the IID system will automatically light the pilot burner first and then the main burner, each
time there is a call for heat from the room thermostat. Whenever the room thermostat is calling for heat, the
circulator supplied with the boiler, will be energized and should be running. The ignition control module will also
be energized to initiate the pilot ignition by opening the first main valve (pilot). At the same time, the electronic
spark generator in the module produces a high voltage spark pulse output that lights the pilot burner. If the pilot
burner does not light, the module will not energize the second main valve and the burners will not light. Ignition
spark continues only until the timed trial for ignition period ends. Then, the module goes into safety shutdown or
lockout. Lockout de-energizes the first main valve operator and closes the first main (pilot) valve in the gas control,
stopping pilot gas flow. The ignition control system must be reset by setting the thermostat below room
temperature for one minute or by turning off power to the module for one minute. When the pilot flame is
established, flame rectification circuit is completed between the sensor and burner ground. The flame sensing
circuit in the module detects the flame current, shuts off the spark generator and energizes the second main valve
operator which opens the second main valve. This allows gas to flow to the burners where it is ignited by the pilot
burner flame. When the thermostat is satisfied, the valve operators are de-energized shutting off the pilot and main
burners, and also the circulator.
CIRCULATOR
VENT SENSOR
BYPASS VALVE
(MODELS 135 & 180 ONLY)
BYPASS LINE
TEMPERATURE
AND PRESSURE GAUGE
2-STAGED CONTROLLER
(MODEL 90 ONLY)
PRESSURE
RELIEF VALVE
RELAY
ADJUSTABLE
HIGH LIMIT
FIELD WIRING
COMPARTMENT
FAST RESPONSE
TEMPERATURE SENSOR
IGNITION MODULE
(AUTO IGNITION ONLY)
TRANSFORMER
ROLL-OUT SENSOR
GAS VALVE
